A skid steer loader is a compact, highly maneuverable vehicle in which the wheels on opposite sides are independently driven. Maneuvering is accomplished by driving the wheels on opposite sides of the vehicle at different speeds and/or in different directions, usually by means of hydrostatic transmissions, to effect propulsion and steering. The operator sits in front of the engine and between a pair of hydraulically actuated loader arms on which a bucket, grapple fork, auger or other accessory can be carried. Suitable controls are provided in the operators compartment for controlling the vehicle and the loader arms, as well as any power accessory mounted on the loader. For effective skid steering, such vehicles must have relatively short wheel bases and treads, and maneuverability is further enhanced by the proper weight ratio between the front and rear axles under loaded and unloaded conditions. Skid steer loaders must therefore be designed for compactness and the desired front/rear axle weight ratio in order to facilitate skid steering as well as handling of loads.
It is desirable to distribute the weight between the axles of skid steer loaders so that the majority of weight is carried by the rear axle when the loader is empty or unloaded, and so that proper balance is maintained when the vehicle is loaded. This in turn means that the engine and related accessories, which comprise a significant amount of the weight, are mounted behind and relatively close to the rear axle. In addition, it is desirable to locate such components as low as possible to lower the center of gravity and thus enhance vehicle stability. Some skid steer loaders incorporate air-cooled engines, however, most utilize liquid-cooled engines whose cooling systems also enter into these design factors.
In the past, a popular approach to the design of cooling systems for skid steer loaders has been to stack the cooling system in longitudinally aligned relationship behind the engine. That is, the fan, radiator and oil cooler are aligned in "stacked" relationship behind the engine. This arrangement, however, is relatively bulky, thus detracting from the overall compactness of the vehicle, and it has also interferred with accessibility to the engine for service, maintenance and the like.
Cooling systems of more compact design have been developed heretofore for skid steer loaders, however, these prior approaches have not been without drawbacks. For example, the Hydra-Mac skid steer loaders include radiators mounted on doors on the rear body. U.S. Pat. No. 3,828,952 shows a skid steer loader wherein the radiator is located above the engine with a pair of fans being provided between the radiator and a grill in the rear body. More recently, U.S. Pat. No. 4,117,902 shows a cooling system for a skid steer loader wherein air is drawn through a rear grill by a fan located ahead of the engine and then blown out through an oil cooler and radiator overlying the engine compartment. While both of these latter two arrangements provide more longitudinal compactness over the axial cooling stacks of the prior art, neither arrangement is adapted to facilitate convenient access to the engine and related accessories for service and the like, or to facilitate cleaning of either the engine radiator and/or the oil cooler. It will be appreciated that skid steer loaders typically operate under adverse conditions which in turn often means higher service and maintenance requirements. The cooling systems of the prior art severely limit access to the engine and related accessories, and require at least partial disassembly for such access and/or cleaning of the radiator or oil cooler, which in turn is time consuming and expensive.
A need has thus arisen for an improved cooling system for a skid steer loader which avoids the drawbacks associated with axially stacked arrangements while affording the advantage of compactness together with better accessibility to the engine, oil cooler and radiator without requiring any disassembly whatever.